Stylus brace for stepback mechanisms



1944. L. THOMPSON ET AL ,360,021

STYLUS BRACE FOR 'STEPBACK MECHANISM Original Filed April 17, 1941 2 Sheets-Sheet 1 ATTORNEY Oct. 19, 1944. v THOMPSON ET AL 2,369,.fi21

STYLUS BRACE FOR STEPBACK MECHANISM Original Filed April 17, 1941 2 Shee'ts$heet 2 32 18 N Is 29 2o 1:: 38 MOTOR 24" L 37 AMPLIFIER INVENTORS L'zjnc'o/n TAom osor; BY Robe/J L. .Sfone ATTORNEY Patented Oct. 10, 1944 STYLUS BRACE FOR STEPBACK- MECHANIS Lincoln Thompson, Cheshire, and Robert L. Stone, Hamden, Conn., assignors to The Soundscriber Corporation, New Haven, 001111., a corporation of Connecticut Original application April 17, 1941, Serial No. 388,956. Divided and this application May 3, 1943, Serial No. 485,480

4 Claims.

This invention relates to improvements in mechanisms for sound reproduction and more particularly to a stylus brace for phonograph stepback mechanism for a transcribing machine employing disk records.

This application is a division of our prior application, Serial No. 388,956, filed April 17, 1941, entitled Stepback mechanism for phonograph transcribers, patented on June 1943, Number 2,323,257.

The present invention is especially designed for dictating machines employing disk records of the type disclosed in Patent No. 2,200,866, issued May 14, .1940, to Lincoln Thompson, on an application filed December 15, 1938, Ser. No. 245,944, entitled Disk dictating machine, reissued September 2, 1942, No, 22,183, and constitutes an improvement over the step-back mechanism disclosed in our prior Patent No. 2,240,321, dated April 29, 1941, entitled Transcribing machine.

In transcribing machines of the above nature, it is often desirable for the typist to play over a portion of the recorded dictation, and the present invention has for its principal object, the provision of an improved form of solenoidoperated step-back mechanism for bask-spacing the pick-up needle a short distance over the record without raising the needle from or stopping the rotation of th turntable.

A further object is to provide means to brace the reproducing needle while the step-back action is taking place.

A still further object of this invention is to provide an improved form of step-back mechanism of the above nature which will be relatively inexpensive to manufacture, simple in construction, compact, ornamental in appearance, and very efficient and durable in use.

With these and other objects in view, which will appear as the description proceeds, there has been illustrated in the accompanying drawings one form in which the invention may be conveniently embodied in practice.

In the drawings:

Figure 1 is a perspective view of a transcribing machine embodying the features and principles of this invention.

Figure 2 is a top plan view on an enlarged scale of the improved step-back mechanism shown in cooperating relation with the reproducing pick-up carrying member.

Figure 3 is a side view of the same, looking in the direction of arrow 3 of Figure 2.

Figure 4 is a front view of a portion of the step-back mechanism, looking in the direction of arrow 4 in Figure 2.

Figure 5 is an enlarged fragmentary top view of a portion of the step-back mechanism illustrating by full and dotted lines three difierent operating positions of the same.

Figure 6 is a fragmentary side view partly in section of the sound reproducing unit and its carrying arm.

Figure 7 is an end view of the same.

Figure 8 is a schematic view of the invention including a diagram of the electrical circuits and control mechanism.

Referring now to the drawings wherein like reference numerals designate like parts throughout the several views, the numeral I0 denotes a casing over which a disk record supporting tumtable II is adapted to rotate. The turntable II is arranged to be driven 'by an electric motor 12 (see Figure 8).

Provision is made of an arm 13, (see Figures 1, 2, 6, and '7), carrying a sound reproducing "pick-up unit M, which is hingedly secured thereto by a fiat leaf spring l5, and also connected .thereto by a coiled counter-balancing spring Iii-said arm l3 being pivoted at I! to the casing top 8 so as to swing over a thin disk record 19 carried by the turntable l. The pickup unit l4 carries a reproducing needle 20 which rides in the sound track previously formed on the surface of the record l9 by a recording machine (not shown) and vibrates said Pick-up unit 14, which is connected by conductors 2| and 22 to the input terminals of a vacuum tube amplifier 23 (see Figure 8). The output terminals of said amplifier 23 lead through conductors 24 and 25, to a loudspeaker or other sound reproducer, not shown.

As herein shown, the back-spacing or stepback means for the pick-up needle includes a fiat frame plate 26 (see Figures 2, 3, 4, and 5), which is adapted to :be adjustably secured upon the casing ID, or to any other suitable stationary part of the transcriber, as 'by a screw 21 extending through an elongated inclined slot 28 formed in said frame 26.

Mounted on the frame 26 is an elehtromagnet generally indicated by the numeral 29, having a U-shaped core 30, the upper leg 3| of which is surrounded by a wire coil 32. The magnet 29 is pivotally secured to the frame member 26 'by a vertical screw pin 33 which passes through the upper leg 3| and lower leg 34 of the core 30 at a point adjacent the curved base of said core.

The coil 32 is adapted to be energized by electric current from a pair of wires LI and L2 through conductors 35 and 38, under the control of a switch 31, preferably hand or foot-operated, and located in circuit with said coil.

Provision is also made of a movable iron armature 38 of light weight which is pivoted to the end of the arm 3| as by a pin 38. The armature 38 is loosely mounted in a slot 48 provided in the free end of the leg 3|, whereby said armature will be supported against lateral movement, and will be carried by the electromagnetic core 38 when the latter swings on its screw pivot pin 33. The armature 38 extends a short distance upwardly beyond the arm 3|, and carries on its outer face, adjacent its upper end, a pointed lug or knife-edge 4| which is adapted to engage with a side bar 48 on the pick-up arm to be described later.

In order to limit the swinging movement of the armature 38 in a direction away from the leg 34, provision is made of a stop finger 42 bent upwardly from the frame 28 into position to be engaged by the lower end of said armature 38, when the core 38 is not magnetized. A coiled tension spring 43 is connected at one end to a fixed angular post 44 preferably secured, at one end, to an upstanding ear 45 on the frame 26 by soldering, or brazing. The other end of the spring 43 is attached to the armature 38 at a point intermediate the upper and lower legs 3| and 34 of the core 38. The spring 43 thus serves to constantly urge the lower end of the armature 38 against the stop finger 42, and also acts to urge the electromagnet core 38 toward the upturned frame ear 45 and into contact with a horizontal adjustable stop screw 48 which is screw-threaded through said ear 45 and is locked thereto by a lock nut 41.

The side bar 48 of the pick-up arm I3 is secured to said arm adjacent the rear end thereof as by rivets and said side arm extends into the path of the upper end of the armature 38 so that whenever the electromagnetic core 38 is magnetized by current passing through the coil 32, the knife-edge U will engage the curved edge 43 on the end of the side bar 48. The edge 43 is curved preferably on an arc struck from the center of the pivot H of the pick-up arm |3, so that when said pick-up arm l3 swings over the record IS, the curved edge 43 will at all times be equidistant from the knife-edge 4|.

In use, when the magnet 28 is energized, the armature or clapper 38, due mainly to its low inertia, will respond quickly to the attraction of the leg 34 of the core 38. The knife-edge 4| will thus engage the arcuate end of the side bar 48 with a biting" action. Shortly, thereafter, due to its higher inertia, the magnet core 38 will be caused to swing backwardly due to a stationary iron post 58 which extends upwardly from the side of the frame plate 28 opposite to the side on which the stop screw 48 is disposed. The force due to the attraction between the legs 3| and 34 of the core 38 and the post 58 will cause the side bar 48 to back-space the pick-up arm any desired number of grooves according to the ad- Justment of the stop screw 48, it being understood that the needle will not be lifted from the record during this action.

The above described combined action of the armature 38 and the magnet core 38 is illustrated in Figure 5 wherein the initial position of the side bar 48 is shown in full lines, and its back-spaced position in dotted lines. It will be understood that upon energization of the coil 32 to magnetize the core member 38, the leg 34 of the magnet core-38 will attract the armature 38, which being relatively light in weight and low in inertia, will be quickly swung about the pivot pin 38, causing the sharp point 5| of the knifeedge 4| to engage the curved end 48 of the thin side bar 48, as indicated at A in Figure 5. The relatively heavy core 38 will be slightly delayed in responding to the magnetic field but will swing on its pivot screw 33 toward and against the armature post 58, as indicated at B in Figure 5, due to the magnetic attraction between the legs 3| and 34 of the core 38 and said post 58. The bar 48 will thus be caused to move from the full line position to the dotted line position as shown in Figure 5. It will be clear from the above explanation that the knife-edge 4| will move in a somewhat angular path, first engaging the edge of the side bar 43, and then moving laterally with said bar through the desired amount of backspacing.

After the switch 31 is opened the armature 38 will be released from the magnetic attraction of the core 38 and will swing quickly due to the action of the spring 43 back into contact with the lug 42. The core 38 will then swing more sluggishly back to its original full line position, shown in Figure 5.

In order to brace and support the needle 28 against being bent when the pick-up unit I4 is stepped-back by the mechanism above described, provision'is made of an angle block 52 secured to the underside of said pick-up unit, Just behind the needle 28 (see Figure 7). The block 52 has a vertical arm 53 which is disposed closely adjacent to the reproducing needle 28, but not so close as to interfere with the normal vibrations thereof.

The pick-up unit used for the transcriber mechanism herein disclosed, should preferably be of the type disclosed in Patent No. 2,213,936, issued September 3, 1940 to Lincoln Thompson, wherein the needle movement is extremely flexible, the brace 52 being essential in order that the movements of the reproducer arm |3 should be transmitted to the needle 28 without excessive backlash, and yet permitting said needle to execute its normal vibrations without striking said brace 52. A further advantage of the use of the brace 52 is that the depending leg 53 will positively jar and vibrate the needle at each actuation so that it will never come to rest in the flat land between two adjacent grooves.

Operation In operation, whenever the typist listening to the loudspeaker reproduction of the record I! in response to the pick-up unit l4 wishes to replay any desired portion of the record, it will only be necessary when this portion has been played to manually close the switch 31, which will be placed in a readily accessible position. The closing of the switch 31 will energize the coil 32, and thus magnetize the core 38, whereupon the light annature 38 will be quickly moved into engagement with the side bar 48. The heavy magnet core 38 will be more slowly swung about its pivot 33 and the combined action of the armature and core will cause the pick-up needle 28 to slide back over the record the predetermined number of grooves. If a greater number of grooves are to be replayed, the switch may be actuated'two or more times in succession.

While there has been disclosed in this specification one form in which the invention may be embodied, it is to be understood that this form is shown for the purpose of illustration only, and that the invention is not to be limited to the specific disclosure, but may be modified and embodied in various other forms without departing from its spirit. In short, the invention includes all the modifications and embodiments coming within the scope of the following claims. Having thus fully described the invention, what is claimed as new and for which it is desired to secure Letters Patent, is:

1. In an electrical phonograph reproducer, a pickup, means to secure a reproducing recordengaging needle having considerable flexibility to said pickup, and a vertical brace plate depending from said pickup in close proximity to said needle and located closely adjacent to the record surface to protect said needle from excessive backlash movements of said pickup and yet permitting it to execute its normal vibrations without striking said brace plate.

2. In an electrical phonograph reproducer, a pickup head. means to secure a laterally-flexible record-engaging needle to said head, means to step-back said needle a predetermined number of grooves to permit that portion of said record to be transcribed, and an angular block secured to said head and having a vertical brace section located in close proximity to said needle to protect the latter from excessive backlash movements of said head and yet permit said needle to execute its normal vibrations without striking said brace section, said vertical brace extending to a point close to the record surface.

3. In an electrical phonograph reproducer, a pickup head, means to secure a laterally-flexible record-engaging needle to said head, means to step-back said needle a predetermined number of grooves to permit that portion of said record to be transcribed, and an angular block secured to said head and having a vertical brace section located slightly in advance of said needle in the direction of its travel to protect the latter from excessive backlash movements 01' said head and yet permit said needle to execute its normal vibrations without striking said brace section, said vertical brace extending to'a point close to the record surface.

4. In a phonograph transcriber, a rotating turntable, a disk record carried by said turntable, a pickup head mounted to swing'across said record, means to secure a depending record-engaging needle having considerable lateral flexibility to said head, means to step-back said needle a predetermined number of grooves to permit that portion of said record to be transcribed, a depending brace carried by said head and located slightly in advance of said needle in the direction of its travel whereby said brace will positively Jar said needle at each actuation of said step-back means so that said needle will never come to rest on the flat land between two adjacent grooves.

LINCOLN THOMPSON. ROBERT L. STONE. 

